import java.util.LinkedList;
import java.util.Queue;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: yinsh
 * Date: 2025-01-23
 * Time: 21:52
 */
public class BinaryTree {
    static class TreeNode {
        public char val;
        public TreeNode left;//左孩子的引用
        public TreeNode right;//右孩子的引用

        public TreeNode(char val) {
            this.val = val;
        }
    }


    /**
     * 创建一棵二叉树 返回这棵树的根节点
     *
     * @return
     */
    public TreeNode createTree() {
        TreeNode root ;
        TreeNode A = new TreeNode('A');
        TreeNode B = new TreeNode('B');
        TreeNode C = new TreeNode('C');
        TreeNode D = new TreeNode('D');
        TreeNode E = new TreeNode('E');
        TreeNode F = new TreeNode('F');
        TreeNode G = new TreeNode('G');
        TreeNode H = new TreeNode('H');
        A.left = B;
        A.right = C;
        B.left = D;
        D.left = E;
        D.right = F;
        C.left = G;
        G.right = H;
        root = A;
        return root;


    }

    // 前序遍历
    public void preOrder(TreeNode root) {
        if (root == null) return;
        System.out.print(root.val + " ");
        preOrder(root.left);
        preOrder(root.right);
    }

    // 中序遍历
    void inOrder(TreeNode root) {
        if (root == null) return;
        inOrder(root.left);
        System.out.print(root.val + " ");
        inOrder(root.right);
    }

    // 后序遍历
    void postOrder(TreeNode root) {
        if (root == null) return;
        postOrder(root.left);
        postOrder(root.right);
        System.out.print(root.val + " ");
    }

    public static int nodeSize;

    /**
     * 获取树中节点的个数：遍历思路
     */
    int size = 0;
    void size(TreeNode root) {
        if (root == null) return;
        size(root.left);
        size(root.right);
        size++;
    }

    /**
     * 获取节点的个数：子问题的思路
     *
     * @param root
     * @return
     */
    int size2(TreeNode root) {
        if (root == null) return 0;
        return size2(root.left) + size2(root.right) + 1;
    }


    /*
     获取叶子节点的个数：遍历思路
     */
    public static int leafSize = 0;

    void getLeafNodeCount1(TreeNode root) {
        if (root == null) return;
        if (root.right == null&&root.left == null) {
            leafSize++;
        }
        getLeafNodeCount1(root.left);
        getLeafNodeCount1(root.right);

    }

    /*
     获取叶子节点的个数：子问题
     */
    int getLeafNodeCount2(TreeNode root) {
        if (root == null) return 0;
        if (root.left == null && root.right == null)
            return 1;
            return getLeafNodeCount2(root.left) + getLeafNodeCount2(root.right);

    }

    /*
    获取第K层节点的个数
     */
    int getKLevelNodeCount(TreeNode root, int k) {
        if (root == null) return 0;
        if (k == 1) return 1;
        return getKLevelNodeCount(root.left,k - 1) + getKLevelNodeCount(root.right,k - 1);

    }

    /*
     获取二叉树的高度
     时间复杂度：O(N)
     */
    int getHeight(TreeNode root) {
        if (root == null) return 0;
        int leftSize = getHeight(root.left);
        int rightSize = getHeight(root.right);
        return leftSize > rightSize ? leftSize + 1: rightSize + 1;
    }


    // 检测值为value的元素是否存在
    TreeNode find(TreeNode root, char val) {
        if (root == null) return null;
        if (root.val == val) {
            return root;
        }else {
            TreeNode left = find(root.left,val);
            if (left == null) {
                TreeNode right = find(root.right,val);
                return right;
            }
            return left;
        }
    }

    //层序遍历
    void levelOrder(TreeNode root) {
        Queue<TreeNode> queue = new LinkedList<>();
        TreeNode top = root;
        if (top == null) return;
        queue.offer(top);
        while (top != null || !queue.isEmpty()) {
            if (top.left != null) {
                queue.offer(top.left);
            }
            if (top.right != null) {
                queue.offer(top.right);
            }
            System.out.print(queue.poll().val + " ");
            top = queue.peek();
        }
    }


    // 判断一棵树是不是完全二叉树
    boolean isCompleteTree(TreeNode root) {
        Queue<TreeNode> queue = new LinkedList<>();
        TreeNode top = root;
        if (top == null) return true;
        queue.offer(top);
        while (top != null && !queue.isEmpty()) {
                queue.offer(top.left);
                queue.offer(top.right);
                queue.poll();
                top = queue.peek();
        }
        while (!queue.isEmpty()) {
            if (top != null) {
                return false;
            }
            top = queue.poll();
         }
        return true;
    }
}
